1. Field of the Invention
The present invention relates to an optical semiconductor device suited to two or more communication formats.
2. Description of the Related Art In recent years, multi-media appliances such as a xe2x80x9csub-note personal computerxe2x80x9d, a portable information terminal, an electronic still camera, etc. have advanced remarkably.
Further, seven millions appliances are sold in a year, and their about 80% adopt an infrared ray system under the IrDA (Infrared Data Association) standard. Therefore, they require transmission/reception between their body and an external system through infrared ray signals. In order to implement such transmission/reception, a light emitting element for emitting infrared rays and a light-receiving element for receiving the infrared rays become necessary.
The optical head used in an optical recording/reproducing apparatus detects a modulated beam emitted from an optical recording medium when it is irradiated with light beams, thereby carrying out recording/reproducing of information. In such a technical field of application also, the light emitting element and the light emitting element are required.
However, compactness of these light-emitting element and light receiving element have not been yet realized. A semiconductor device (module) as shown in FIG. 5 has been proposed in Japanese Patent Publication. No. 7-28085 in which a semiconductor laser 1 is directly connected to a semiconductor substrate 2 and a prism having a trapezoidal shape in section is secured to the semiconductor substrate 2. Reference numeral 4 denotes an optical recording medium.
A slanted face 5 of the prism 3 opposite to the semiconductor laser 1 is a semi-transparent reflection face. The area of a prism face 6 abutting on the semiconductor substrate 2, other than that of an optical detector (light receiving element) 7 is a reflecting face. A prism face 8 opposite to the prism face 6 is also the reflecting face.
A light beam 9 is emitted from the semiconductor laser 1 and incident on the prism 3 through the slanted face 5. The light beam 9 is reflected by the reflecting faces 6 and 8 and detected by the optical detector 7.
On the other hand, an infrared ray data communication module which is a typical conventional optical semiconductor device as shown in FIG. 6 has been proposed in JP-A-10-70304. It is a module M incorporating an infrared ray LED, an LED driver, a PIN photodiode, an amplifier, etc. For example, the LED is mounted on a substrate formed in the module. The light emitted from the LED is externally emitted through a lens L1 attached on the upper face of the module M. The photodiode is also mounted on the substrate. The light from the photodiode is incident on the module M through a lens L2 attached to the upper face of the module M. Such a module is mounted on a printed board equipped with an optional circuit. These modules have the following defects. The module shown in FIG. 5, in which an optical device is mounted on the semiconductor substrate, requires a very sophisticated technique to manufacture and is very expensive. The module shown in FIG. 6 requires for light to be taken in/out from above the module, and hence another optical semiconductor to be located. The system incorporating these components increases its thickness and hence cannot be miniaturized.
Meanwhile, the various appliances described above use the remote control standard as an infrared ray day communication system instead of the above IrDA. In the IrDA and remote control, the wavelength of the infrared rays used in each of the appliances varies according to the standard. The wavelength is 950 nm in the IrDA standard, and 870 nm in the remote control standard. Because of such a difference in wavelength, conventionally, LEDs having different wavelengths were used individually. Therefore, in the appliance using both IrDA and remote control standards, the number of IC""s to be used increases. This hinders such an appliance from being miniaturized.
Further, the outer shape of the module also hinders realization of the compactness. Specifically, in the modules as shown in FIGS. 5 and 6, the optical device is mounted on the semiconductor substrate, and the lens is mounted on the module with the semiconductor substrate molded. Therefore, the set incorporating these modules cannot be miniaturized.
Further, in the module shown in FIG. 6, in which the lens is attached to the upper face of the module, light cannot be taken in or out in only a direction perpendicular to a printed board. Therefore, when the module is built in the above appliance, the printed board must be grounded perpendicularly to the direction of taking in or out light. This also hinders the compactness of the appliance from being realized. In a low-profiled portable appliance, it is difficult to take out or in light from the side wall of the appliance. The present invention has been accomplished in order to solve the above problems described above.
An object of the present invention is to provide an optical semiconductor device which can transmit or receive signals in a plurality of different communication formats, can be easily manufactured to provide its compactness and low-profiling.
In order to attain the above object, in accordance with a first aspect of the present invention, there is provided an optical semiconductor device capable of receiving data in a first and a second communication format which are different from each other, comprising: a light receiving element for receiving input data in the first and the second communication format; a first signal processing circuit for processing an output signal from the light receiving element when input data in the first communication format is received; and a second signal processing circuit for processing the output signal from the light receiving element when input data in the second communication format is received.
Preferably, the first signal processing circuit includes a signal transferring means processing the output signal from the light receiving element and transferring a wave-shaped signal to a rear stage circuit.
Preferably, the second signal processing circuit includes a detecting means for detecting an output signal from the light receiving element and a signal transferring means transferring an output signal from the detecting means.
Preferably, the first communication format is an IrDA communication and the second communication format is a remote control communication.
Preferably, the optical semiconductor device comprises a first semiconductor chip in the light receiving element, the first and the second signal processing circuit are integrated on the same semiconductor substrate; a resin sealing body which seals the first semiconductor chip with a light receiving face of the light receiving element oriented upward and is transparent to a prescribed wavelength of light; and a light reflecting face formed on the resin sealing body on the first semiconductor chip and crossing a normal line to the light receiving face at a prescribed angle, wherein a side wall of the resin sealing body serves as a light receiving face.
Preferably, the optical semiconductor device further comprises: a light emitting element for emitting light having a prescribed wavelength in order to transmit data in the first and the second communication format which are different from each other; and a driving circuit which is changed in its driving capability according to the communication format and is adapted to drive the light emitting element according to the input data.
Preferably, the driving circuit is designed so that the driving capability is low in the IrDA communication and is high in the remote control communication.
Preferably, the optical semiconductor device further comprises a second semiconductor chip on which the light emitting element is integrated, the second semiconductor chip being integrally resin-sealed on the resin sealing body so that the reflecting face crosses a normal line to the light emitting element at:a prescribed angle, and the side wall of the resin sealing body serves as a light emitting face.
Preferably, the driving circuit is integrated on the first semiconductor chip.
In accordance with the second aspect of the present invention, there is provided an optical semiconductor device capable of receiving data in a first and a second communication format which are different from each other, comprising: a light emitting element for emitting light having a prescribed wavelength; a driving circuit which is changed in its driving capability according to the communication format and is adapted to drive the light emitting element according to the data.
Preferably, the wavelength of the light corresponds to one of the communication formats.
Preferably, the driving circuit includes a plurality of driving transistors corresponding to the communication formats, resistors connected to emitters of the driving transistors, respectively to determine values of driving currents from the driving transistors; and a switching means for selecting one of the driving transistors according to the communication format.
Preferably, at least one of the resistors is an external resistor.
Preferably, the first communication format is an IrDA communication and the second communication format is a remote control communication.
Preferably, the driving circuit is designed so that the driving capability is low in the IrDA communication and is high in the remote control communication.
Preferably, the optical semiconductor device comprises: a second semiconductor chip on which the light emitting element is integrated on a semiconductor substrate; a resin sealing body for sealing the second semiconductor chip with a light emitting face of the light emitting element oriented upward and is transparent to a prescribed wavelength of light; and a light reflecting face formed on the resin sealing body on the second semiconductor chip and crossing a normal line to the light emitting face at a prescribed angle, wherein a side wall of the resin sealing body serves as a light emitting face.
Preferably, the driving circuit is integrated on a first semiconductor chip which is different from the second semiconductor chip on which the light emitting element is mounted and sealed integrally to the resin sealing body.
In accordance with the third aspect of the present invention, there is provided an optical semiconductor device according to the first aspect, comprising: a first semiconductor chip on which a light emitting element with its upper face oriented upward is mounted; a second semiconductor chip on which the light receiving element with a light receiving element oriented upward, the first and the second signal processing circuit for processing an output signal from the light receiving element and a driving circuit for driving the light emitting element are integrated on the same semiconductor substrate; a resin sealing body which seals the first and the second semiconductor chip with the light receiving and emitting faces oriented upward and is transparent to a prescribed wavelength of light; and a light reflecting face formed on the resin sealing body on the first and the second semiconductor chip and crossing a normal line to the light receiving and emitting faces at a prescribed angle, wherein a side wall of the resin sealing body serves as a light receiving or emitting face.
Preferably, the first and the second semiconductor chip are integrally sealed within the resin sealing body.
Preferably, the first and the second semiconductor chip are sealed in a first and a second resin sealing body, respectively.
Preferably, the signal processing circuit is a current/voltage converting circuit for converting an output current from the light receiving element into a voltage.
The present invention provides an optical semiconductor device capable of transmitting or receiving signals in a plurality of communication formats which are different from one another. In the configurations described above, the present invention realizes its miniaturizing and low-profiling at low cost. The optical semiconductor device according to the present invention includes signal processing circuits capable of processing received data in two different communication formats and/or a driving circuit for driving the light emitting element so as to emit light, and comprises a semiconductor chip on which the light receiving element and/or light emitting element, a sealing body which seals the semiconductor chip and is arranged to provide a reflecting face with a prescribed angle from the light emitting face or light receiving face so that an optical passage of incident light or emitting light is bent through the reflecting face. Such a configuration contributes to miniaturization and low-profiling of the optical semiconductor device.
Particularly, incidence and emission of light can be made from the side wall of the sealing body through the reflecting face, thereby further facilitating the low-profiling. By providing the sealing body with a means having a reflecting face separately or integrally, with the optical semiconductor device located horizontally, the incident light or emitting light is made horizontal. Thus, the positioning accuracy of the optical passage of light is improved. Further, if these optical semiconductor devices are located at opposite positions, optical communication can be made in a horizontal direction.
Since light can be emitted from the upper face of the sealing body through the reflecting face, if the sealing body is provided with the means having a reflecting face separately or integrally, with the optical semiconductor device located horizontally, the incident light or emitting light is made vertical. This greatly contributes to cost reduction.
In accordance with the present invention, since a single pair of light emitting element and light receiving element can transmit/receive various kinds of infrared rays data, the number of components in the appliance can be reduced. This greatly contributes to miniaturizing and low-profiling of a set of devices constituting an appliance.
Since the groove is formed in the resin sealing body so that it provides the reflecting face, light is emitted from the side of the resin sealing body. Therefore, the optical semiconductor device can be miniaturized and low-profiled, thereby permitting the set appliance using such an optical semiconductor device to be miniaturized and low-profiled.
The above and other objects and features of the present invention will be more apparent from the following description taken in conjunction with the accompanying drawings.
FIG. 1 is a block diagram showing an embodiment of the present invention;
FIG. 2 is a circuit diagram showing a typical circuit of a driving circuit 14 in FIG. 4;
FIG. 3 is a block diagram showing a circuit on the receiving side in FIG. 1;
FIGS. 4A and 4B are a plan view and sectional view showing package for resin-sealing the circuit shown in FIG. 1, respectively;
FIG. 5 is a sectional view of a prior art; and
FIG. 6 is a perspective view of another prior art.